Assessing the Impact of Nature-Based Solutions on Water Resources: A Catchment Scale Modeling Approach

Climate and environmental changes are impacting the hydrological water cycle, affecting water availability and having negative consequences for water security. There are numerous practices in place to address this challenge, one of which is utilizing nature in the form of Nature-based Solutions (NbS). NbS include various interventions, such as green roofs, urban wetlands, permeable pavements, and restored riparian corridors, all inspired by, supported by, or mimicking nature. NbS are emerging as a transformative approach that leverages ecological processes to address societal challenges while delivering multiple co-benefits. However, the application of NbS at a large scale, e.g., Catchment scale, is a challenging task due to constraints in the practicality of these solutions. One major challenge is identifying potential solutions and modeling the impact of these solutions, which seems a straightforward task but presents practical difficulties.

This study focuses on identifying and quantifying the impact of solutions on water availability utilizing the DREAM hydrological model. The case study is conducted in the German catchment, the Bode River Basin. Water management in the Bode is a crucial issue for authorities, as it faces extreme events such as droughts and has experienced significant deforestation in recent years. This approach first identified the potential NbS for the catchment using the catchment-scale framework (Sarwar et al., 2025). Then, those selected solutions were modeled, such as the construction of an infiltration basin, using the site's ecological features. Then, to evaluate the effect of these interventions on the water budget, baseline (without solutions) scenarios were compared to scenarios with solutions. Results showed that the total discharge of the basin is significantly affected, with a 5-10 percent decrease in flows. However, in the locations where infiltration basins were constructed, there has been a higher reduction in runoff volume and an increase in groundwater recharge.